Error using textscan Invalid file identifier Use fopen to generate a valid file identifier in app designer

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sydney salvador 2020-4-28

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https://ww2.mathworks.cn/matlabcentral/answers/521518-error-using-textscan-invalid-file-identifier-use-fopen-to-generate-a-valid-file-identifier-in-app-de

评论： sydney salvador 2020-5-1

I use a button to upload my "Data.txt" file and another button to calculate and plot it into UIaxes but im having error in "fid=fopen"

properties (Access = public)
        selectpath='';
    end
    
    % Callbacks that handle component events
    methods (Access = private)
        % Button pushed function: UploadButton
        function UploadButtonPushed(app, event)
            [file,path] = uigetfile('*.txt')
        end
        % Button pushed function: CalculateButton
        function CalculateButtonPushed(app, event)
fid=fopen(Data.txt(app.selectpath));
fclose(fid);                                    %Error using textscan 
                                                % Invalid file identifier. 
                                                % Use fopen to generate a valid file identifier.
seek=textscan(fid,'%f %f','headerlines',2);
g = cell2mat(seek);
x=g(:,1);
y=g(:,2);
[sortedX, sortIndex] = sort(x);
sortedY = y(sortIndex);
          sortedXLimit = sortedX(1:160,:);
          sortedYLimit = sortedY(1:160,:);
plot(app.UIAxes,value*peaks)                %for the graph
app.UIAxes.YLim = [0 205];

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darova 2020-4-30

Try this

sydney salvador 2020-4-30

i has the same error

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采纳的回答

Tommy 2020-4-30

2
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https://ww2.mathworks.cn/matlabcentral/answers/521518-error-using-textscan-invalid-file-identifier-use-fopen-to-generate-a-valid-file-identifier-in-app-de#answer_429474

编辑：Tommy 2020-4-30

在 MATLAB Online 中打开

It doesn't seem like your upload button stores anything. It saves the file and path into file and path and then exits, at which point the file and path are lost. This would work:

function UploadButtonPushed(app, event)
    [file,path] = uigetfile('*.txt');
    if file == 0
        % handle case where user clicks cancel
    else
        app.selectpath = fullfile(path, file);
    end
end

And then in your other callback:

function CalculateButtonPushed(app, event)
    fid=fopen(app.selectpath);
    seek=textscan(fid,'%f %f','headerlines',2);
    ...

10 个评论
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Tommy 2020-5-1

在 MATLAB Online 中打开

Hmm... I'll assume you want to plot your sorted and trimmed y over your sorted and trimmed x, in which case you should try

plot(app.UIAxes,sortedXLimit,sortedYLimit)

If that's not what you want, could you provide the code which worked for you?

sydney salvador 2020-5-1

Thank you sir it has worked now

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更多回答（1 个）

sydney salvador 2020-5-1

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/521518-error-using-textscan-invalid-file-identifier-use-fopen-to-generate-a-valid-file-identifier-in-app-de#answer_429626

在 MATLAB Online 中打开

[sortedX, sortIndex] = sort(x);
sortedY = y(sortIndex);
          sortedXLimit = sortedX(1:160,:);
          sortedYLimit = sortedY(1:160,:);
           plot(app.UIAxes,sortedXLimit,sortedYLimit)          
           app.UIAxes.YLim = [0 1000];
           hold on
           findpeaks(sortedYLimit,sortedXLimit,'MinPeakProminence',205,'Annotate','extents')